Free radicals occur in various physiological processes, and semiquinones are widespread and intimately involved in biological electron transfer processes. In order to extract more information about this, we investigated a number of semiquinone radicals with the 96Ghz (W-band) EPR spectrometer. At this high magnetic field, the increased Zeeman interaction can separate 'g' and 'a' tensors. The quinone systems examined so far include benzoquinone, catechol, methylcatechol, DOPA and DOPAMINE. Also, the effect of solvents on the 'g' tensor has been studied. It has been found that when going from protic to aprotic solvent there is an increase in 'g' values. Thus the formation of hydrogen bonds is of particular importance for better understanding of the role of free radicals of quinones in in vivo systems. We have examined a few proteins and are planning to carry out these studies on some more proteins which generate semiquinone radicals.